The patch titled
Mempolicy: update stale documentation and comments
has been added to the -mm tree. Its filename is
mm-filter-based-on-a-nodemask-as-well-as-a-gfp_mask-doc-fixes.patch
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------------------------------------------------------
Subject: Mempolicy: update stale documentation and comments
From: Lee Schermerhorn <Lee.Schermerhorn@xxxxxx>
Address stale comments and numa_memory_policy.txt discussion based on Mel
Gorman's changes to page allocation zonelist handling.
Specifically: mpol_free() and mpol_copy() no longer need to deal with a custom
zonelist for MPOL_BIND policy, and MPOL_BIND now allocates memory from the
nearest node with available memory in the specified nodemask.
In "fixing" the mpol_free() and mpol_copy() comments in mempolicy.h, I wanted
to replace them with something, rather than just deleting them. So, I
described the reference counting. Not directly related to the zonelist
changes, but useful, IMO.
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
Acked-by: Paul Jackson <pj@xxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Christoph Lameter <clameter@xxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Hugh Dickins <hugh@xxxxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/vm/numa_memory_policy.txt | 11 +++--------
include/linux/mempolicy.h | 8 +++++---
2 files changed, 8 insertions(+), 11 deletions(-)
diff -puN Documentation/vm/numa_memory_policy.txt~mm-filter-based-on-a-nodemask-as-well-as-a-gfp_mask-doc-fixes Documentation/vm/numa_memory_policy.txt
--- a/Documentation/vm/numa_memory_policy.txt~mm-filter-based-on-a-nodemask-as-well-as-a-gfp_mask-doc-fixes
+++ a/Documentation/vm/numa_memory_policy.txt
@@ -182,14 +182,9 @@ Components of Memory Policies
The Default mode does not use the optional set of nodes.
MPOL_BIND: This mode specifies that memory must come from the
- set of nodes specified by the policy.
-
- The memory policy APIs do not specify an order in which the nodes
- will be searched. However, unlike "local allocation", the Bind
- policy does not consider the distance between the nodes. Rather,
- allocations will fallback to the nodes specified by the policy in
- order of numeric node id. Like everything in Linux, this is subject
- to change.
+ set of nodes specified by the policy. Memory will be allocated from
+ the node in the set with sufficient free memory that is closest to
+ the node where the allocation takes place.
MPOL_PREFERRED: This mode specifies that the allocation should be
attempted from the single node specified in the policy. If that
diff -puN include/linux/mempolicy.h~mm-filter-based-on-a-nodemask-as-well-as-a-gfp_mask-doc-fixes include/linux/mempolicy.h
--- a/include/linux/mempolicy.h~mm-filter-based-on-a-nodemask-as-well-as-a-gfp_mask-doc-fixes
+++ a/include/linux/mempolicy.h
@@ -54,11 +54,13 @@ struct mm_struct;
* mmap_sem.
*
* Freeing policy:
- * When policy is MPOL_BIND v.zonelist is kmalloc'ed and must be kfree'd.
- * All other policies don't have any external state. mpol_free() handles this.
+ * Mempolicy objects are reference counted. A mempolicy will be freed when
+ * mpol_free() decrements the reference count to zero.
*
* Copying policy objects:
- * For MPOL_BIND the zonelist must be always duplicated. mpol_clone() does this.
+ * mpol_copy() allocates a new mempolicy and copies the specified mempolicy
+ * to the new storage. The reference count of the new object is initialized
+ * to 1, representing the caller of mpol_copy().
*/
struct mempolicy {
atomic_t refcnt;
_
Patches currently in -mm which might be from Lee.Schermerhorn@xxxxxx are
fix-mempolicy-reference-counting-bugs.patch
mm-filter-based-on-a-nodemask-as-well-as-a-gfp_mask-doc-fixes.patch
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